1. Field of the Invention
This invention relates generally to drill bits and more particularly, but not by way of limitation, to rotary drill bits having tapered cutting surfaces.
2. Description of the Prior Art
In drilling operations, such as those which occur in constructing an oil and/or gas well, the types of drill bits used frequently have relatively horizontally disposed cutting surfaces whereby the cutting of the workpiece occurs over a surface area approximately equal to only the cross-sectional area of the drill bit. To increase the surface area which is contacted by the cutting surface of the drill bit, it is necessary to provide a tapered cutting surface on the drill bit. To further enhance the cutting ability of the drill bit, it is desirable to provide a plurality of sharp edges along the tapered cutting surface. So that the taper can be retained on the drill bit as the drill bit wears during use, it is further desirable to provide the drill bit with a construction which maintains its tapered cutting surface even as it wears. Additionally, it is desirable to make such a drill bit structurally strong by having the cutting members include solid wall structures along the entire longitudinal cutting length of the drill bit.
U.S. Pat. No. 2,203,747 in the name of Sandstone discloses a laminated disk drill bit which, in the embodiment shown in FIG. 2 of the Sandstone patent, has a conically shaped cutting face. However, the cutting members are comprised of a plurality of longitudinally stacked cutting disks which are connected by suitable fastener means. Therefore, the Sandstone device fails to include cutting members which comprise single structures extending along the entire cutting length of the drill bit.